CVE-2023-32423: Apple Safari Buffer Overflow Vulnerability

CVE-2023-32423 Overview

CVE-2023-32423 is a buffer overflow vulnerability affecting multiple Apple products including Safari, iOS, iPadOS, macOS, watchOS, and tvOS. The vulnerability exists in the WebKit browser engine and can be exploited when a user processes maliciously crafted web content. Successful exploitation allows an attacker to disclose sensitive information from the victim's device through improper memory handling operations.

Critical Impact

Processing malicious web content may lead to sensitive information disclosure across Apple devices including iPhones, iPads, Macs, Apple Watches, and Apple TVs.

Affected Products

• Apple Safari versions prior to 16.5
• Apple iOS and iPadOS versions prior to 16.5
• Apple macOS Ventura versions prior to 13.4
• Apple watchOS versions prior to 9.5
• Apple tvOS versions prior to 16.5

Discovery Timeline

• June 23, 2023 - CVE-2023-32423 published to NVD
• March 20, 2025 - Last updated in NVD database

Technical Details for CVE-2023-32423

Vulnerability Analysis

This vulnerability is classified as CWE-120 (Buffer Copy without Checking Size of Input), commonly known as a classic buffer overflow. The flaw resides in Apple's WebKit rendering engine, which powers Safari and provides web rendering capabilities across all Apple operating systems. When processing specially crafted web content, the affected components fail to properly validate buffer boundaries, allowing data to be read beyond intended memory regions.

The network-based attack vector requires user interaction—specifically, a victim must visit a malicious webpage or process attacker-controlled web content. While the vulnerability does not allow an attacker to modify data or cause system crashes, it enables high-impact confidentiality breaches where sensitive information stored in memory could be extracted.

Root Cause

The root cause stems from insufficient bounds checking during memory copy operations within WebKit's content processing routines. When handling certain web content structures, the code fails to verify that the input data size does not exceed the allocated buffer capacity. This oversight allows read operations to access memory locations beyond the intended buffer boundaries, potentially exposing sensitive data residing in adjacent memory regions.

Attack Vector

The attack is network-based and requires user interaction. An attacker could exploit this vulnerability through several methods:

1. Malicious Website: Hosting a webpage containing specially crafted content designed to trigger the buffer overflow
2. Malicious Advertisement: Injecting exploit code through advertising networks displayed on legitimate websites
3. Phishing Campaigns: Distributing links to malicious content via email or messaging platforms
4. Watering Hole Attacks: Compromising websites frequently visited by targeted users

Upon visiting the malicious content, the victim's browser processes the crafted data, triggering the out-of-bounds read operation. The attacker can then exfiltrate sensitive information that may include authentication tokens, session data, or other confidential information residing in the browser's memory space.

Detection Methods for CVE-2023-32423

Indicators of Compromise

• Unusual WebKit process memory access patterns or crashes
• Unexpected network traffic from Safari or WebKit-based applications to unknown external hosts
• Browser-based processes accessing memory regions outside normal operational parameters
• Anomalous JavaScript execution patterns in web content processing logs

Detection Strategies

• Monitor system logs for WebKit-related crashes or memory access violations
• Implement network traffic analysis to detect potential data exfiltration attempts from browser processes
• Deploy endpoint detection solutions capable of identifying abnormal memory access patterns in web rendering engines
• Utilize browser security extensions that block suspicious web content

Monitoring Recommendations

• Enable enhanced logging for WebKit processes on managed Apple devices
• Monitor for connections to recently registered or suspicious domains from Safari and other WebKit-based applications
• Implement Mobile Device Management (MDM) policies to receive alerts on Safari crashes or abnormal behavior
• Configure SentinelOne agents to monitor WebKit processes for memory-related anomalies

How to Mitigate CVE-2023-32423

Immediate Actions Required

• Update all Apple devices to the latest patched versions immediately (Safari 16.5, iOS 16.5, iPadOS 16.5, macOS Ventura 13.4, watchOS 9.5, tvOS 16.5)
• Enable automatic updates on all Apple devices to ensure timely deployment of security patches
• Educate users about the risks of visiting untrusted websites and clicking suspicious links
• Consider implementing content filtering or web proxy solutions to block access to known malicious domains

Patch Information

Apple has addressed this vulnerability in the following security updates:

• Apple Security Update HT213757 - Safari 16.5
• Apple Security Update HT213758 - iOS 16.5 and iPadOS 16.5
• Apple Security Update HT213761 - macOS Ventura 13.4
• Apple Security Update HT213762 - tvOS 16.5
• Apple Security Update HT213764 - watchOS 9.5

The patches implement improved memory handling to properly validate buffer boundaries before performing copy operations.

Workarounds

• Use alternative browsers on macOS that do not rely on WebKit (note: on iOS, all browsers use WebKit)
• Implement network-level web content filtering to reduce exposure to malicious websites
• Disable JavaScript in Safari for untrusted websites using Content Blockers or Safari settings
• Restrict web browsing on sensitive systems until patches can be applied

# Check Safari version on macOS
/Applications/Safari.app/Contents/MacOS/Safari --version

# Check macOS version
sw_vers -productVersion

# Check iOS/iPadOS version via command line on managed devices
# Using Apple Configurator or MDM solution reporting